### What problem were solved in this pull request?
ref #138 

Problem:

SEDA的线程池模式是每个处理环节分开，可能会放到不同的线程上，也可以调整不同stage对应的处理线程个数。但是会增加复杂性，比如session会切换线程、代码逻辑复杂。

### What is changed and how it works?
去掉了parse、resolve等stage，仅保留了session stage。代码中的名字依然叫stage，后续再调整。
在session
stage的处理逻辑中，直接调用其它流程处理，这样也使SQL处理流程变得更清晰。后续还可以考虑移除observer.ini，所有参数均通过命令行传递。

### Other information

### What problem were solved in this pull request?

Problem:
与训练营配合，可以在SQL命令请求过程中，添加调试信息

### What is changed and how it works?
可以参考 debug-output.md 文档。
增加 sql_debug 变量，使用set sql_debug=1; 可以设置。
在SQL命令执行过程中，调用sql_debug函数，增加调试信息。在普通文本通讯协议中，调试信息会以 '#'
开头的形式打印出来。但是注意调试信息中不要带换行符。

### Other information

### What problem were solved in this pull request?

Issue Number: close #142 

Problem:
value和tuple_cell的语义是重合的，所以代码时冗余的

### What is changed and how it works?
删除tuple_cell，都使用value来替换，并将tuple_cell中的接口都在value中实现

### Other information

### What problem were solved in this pull request?

Issue Number: close #192 

Problem:
clang 14编译失败

### What is changed and how it works?
修复编译错误

### Other information

logical plan & physical plan;
explain;
yacc rewrite;
join operator(nested loop join);
simple rewrite rules;
fix some issues of mysql protocol;

tested by mariadb ( Ver 15.1 Distrib 5.5.65-MariaDB, for Linux (x86_64) using readline 5.1)
but failed with obclient